This invention relates generally to consumer sprays that contain ethanol as a solvent for active ingredients in the spray, and to the replacement of ethanol by alkyl acetates, especially methyl acetate and t-butyl acetate. The invention also has application to consumer sprays that contain isopropanol, and the replacement of isopropanol by these alkyl acetates.
Hair sprays were introduced to the public in the late 1940""s and were an immediate success. The first sprays were pump type systems, but public demand for a better product caused the development of the aerosol spray. The aerosol spray was based on Goodhue and Sullivan""s patent of low-pressure propellants (fluorocarbon 12) and Abplanalp""s patented valve design. The first aerosol hairspray was introduced to the public in 1949 in Chicago by the Global Liqinet Corporation, and created a multi-billion dollar business.
Shellac was the first fixative polymer used in aerosols; but shellac had several major drawbacks that led to the development of synthetic polymers with properties that could be better controlled. Many of the formulations gave good fixative properties, but contained environmentally sensitive solvents and propellants. In 1979 chlorofluorocarbon (CFC) propellants were banned from aerosol formulations in most industrialized nations, and manufacturers began removing the popular co-solvent methylene chloride from hair spray formulations. Ethyl alcohol and alcohol/water systems replaced methylene chloride in the solvent system of many hair sprays. Dimethyl ether and 80/20 isobutane/propane replaced CFCs in the propellant systems of many aerosol sprays. However, these propellants and solvents are VOCs (volatile organic compounds) and must be considered as such in the hair spray formulations in which they are used.
The United States Environmental Protection Agency (EPA) has mandated a reduction in the VOC content of hair sprays to 80% or less by 1998. Furthermore, Section 183(e) of the United States Clean Air Act Amendments of 1990 required the EPA to develop a control strategy for reducing VOC emissions from consumer and commercial products that takes into account the ozone-forming potential or xe2x80x9creactivitiesxe2x80x9d of such emissions. In 1992, the EPA published requirements for State Implementation Plans to reduce VOC emissions. The policy gave a definition of xe2x80x9cvolatile organic compoundxe2x80x9d which excluded specific VOC species of negligible reactivity, and made the distinction between xe2x80x9creactivexe2x80x9d VOCs and xe2x80x9cnegligibly reactivexe2x80x9d VOCs. Currently, the EPA favors distinguishing between xe2x80x9creactivexe2x80x9d and xe2x80x9cnegligibly reactivexe2x80x9d based on whether a species has greater or less atmospheric reactivity compared to ethane. The state of California has set an even more stringent requirement for VOCs in hair spray than the EPA, limiting VOCs to 55% by June 1999.
Currently, the major solvent in most hair sprays is ethyl alcohol and is present in the amounts of 60% to 95% depending on whether the spray is aerosol or pump type. Ethanol solubilizes the polymer systems and provides an optimum delivery system that is easy to use, and dries quickly on application. In addition, ethanol has a pleasant smell, and has no serious toxicological constraints on use. However, alcohol is a VOC and is accounted as such in hair spray systems. To lower the VOC content of the spray, many manufacturers have replaced ethanol in their sprays with water. However, an increase in the water concentration can adversely affect the performance of the hair spray by accelerating the initial curl droop and/or increasing the dry time on the hair.
Manufacturers have recited numerous laundry lists of solvents that theoretically could be used in a hair spray. For example, U. W. E. Bergemann, et al, (U.S. Pat. No. 4,243,548) discloses a pressurized aerosol formulation in which the solvent can be one of 21 compounds, or any mixture of these compounds. Listed compounds include ethyl methyl ketone, dimethoxy methane, diethyl carbonate, n-propanol, ethyl chloride, 1,1-dichloroethane, 1-chlorobutane, ethanol, isopropanol, diethyl ether, acetone, and methyl acetate among others. Other patents provide similar listings of solvents. See, e.g., U.S. Pat. No. 5,686,066 to Harada et al., U.S. Pat. No. 5,605,647 to Nimitz et al., and U.S. Pat. No. 4,173,627 to Madrange et al. Most of these chemicals would be undesirable to consumers or manufacturers for use in personal care products such as hair spray. For example, some of the solvents, such as the acetates, hydrolyze in the presence of water to form harmful acids. Many of the solvents have pungent chemical odors, or stain clothing. As a result, ethanol and water remain the predominant solvents of choice for consumer hair spray formulations.
Applicants have unexpectedly discovered that the cosmetically unacceptable odor associated with alkyl acetates such as methyl acetate is substantially reduced when combined with alcohols such as ethanol, and that alkyl acetates can thus replace some of the alcohol in consumer spray formulations without lessening consumer acceptance. Applicants have also unexpectedly discovered that ethanol inhibits the hydrolysis of methyl acetate in the presence of water, thereby reducing the formation of harmful acids in formulations that contain water. Ethanol also inhibits the detrimental effects that methyl acetate by itself can cause to some fabrics.
Thus, certain alkyl acetates (particularly methyl acetate and/or t-butyl acetate) unexpectedly can be used to replace part of the alcohol (particularly isopropanol and/or ethanol) in consumer spray formulations without adversely affecting the performance, odor, or shelf stability of the hair spray. This is an important consideration, because methyl acetate is a xe2x80x9cnegligibly reactivexe2x80x9d VOC and is thus more environmentally acceptable than ethanol. Measurements show that methyl acetate generates 0.03 gram ozone per gram solvent, compared to ethanol which generates 0.42 gram ozone per gram solvent. Thus it is possible to formulate an improved hair spray providing most of the properties considered desirable for hair grooming and having a lower potential to generate ground-level ozone.
In accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a hair care composition comprising a fixative, ethanol, and methyl acetate and/or t-butyl acetate.
In another aspect the invention provides a consumer article comprising a hand-held spray container, and a sprayable composition contained within the spray container comprising ethanol and methyl acetate.
In yet another aspect the invention provides a consumer article comprising a hand-held spray container, and a sprayable composition contained within the spray container comprising isopropanol and methyl acetate.
In still another aspect the invention provides a method of fixing hair comprising spraying the compositions of this invention onto hair.
These and other objects of this invention are achieved in hair spray and consumer spray formulations which:
(1) release reduced amounts of reactive VOCs into the atmosphere;
(2) have good storage stability and produce a limited amount of corrosive acidic products upon aging; and
(3) are not tacky, and have a fast drying rate, low odor, and acceptable viscosity and curl retention.
Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.